// since Go maps never free memory.
const mapReInitializeThreshold = 1000

type userNsPodsManager interface {
	HandlerSupportsUserNamespaces(runtimeHandler string) (bool, error)
	GetPodDir(podUID types.UID) string
	ListPodsFromDisk() ([]types.UID, error)
	GetKubeletMappings() (uint32, uint32, error)
	GetMaxPods() int
}

type UsernsManager struct {
	used    *allocator.AllocationBitmap

func (kl *Kubelet) GetPodDir(podUID types.UID) string {
	return kl.getPodDir(podUID)
}

// ListPodsFromDisk gets a list of pods that have data directories.
func (kl *Kubelet) ListPodsFromDisk() ([]types.UID, error) {
	return kl.listPodsFromDisk()
}

// HandlerSupportsUserNamespaces checks whether the specified handler supports
// user namespaces.

}

func (m *testUserNsPodsManager) GetPodDir(podUID types.UID) string {
	if m.podDir == "" {
		return "/tmp/non-existant-dir.This-is-not-used-in-tests"
	}
	return m.podDir
}

func (m *testUserNsPodsManager) ListPodsFromDisk() ([]types.UID, error) {
	if len(m.podList) == 0 {
		return nil, nil
	}
	return m.podList, nil
}

func (m *testUserNsPodsManager) HandlerSupportsUserNamespaces(runtimeHandler string) (bool, error) {

	allPods := sets.New[string]()
	for _, pod := range pods {
		allPods.Insert(string(pod.UID))
	}
	for _, pod := range runningPods {
		allPods.Insert(string(pod.ID))
	}

	found, err := kl.listPodsFromDisk()
	if err != nil {
		return err
	}

	orphanRemovalErrors := []error{}
	orphanVolumeErrors := []error{}
	var totalPods, errorPods int

	for _, uid := range found {

		return 0, 0, fmt.Errorf("mismatched subuids and subgids for user %q", kubeletUser)
	}
	return parseGetSubIdsOutput(string(outUids))
}

// Get a list of pods that have data directories.
func (kl *Kubelet) listPodsFromDisk() ([]types.UID, error) {
	podInfos, err := os.ReadDir(kl.getPodsDir())
	if err != nil {
		return nil, err
	}
	pods := []types.UID{}
	for i := range podInfos {
		if podInfos[i].IsDir() {